Results 1 to 4 of 4

Math Help - Application problems are really starting to annoy me...

  1. #1
    Member
    Joined
    Dec 2007
    From
    Georgia
    Posts
    85

    Application problems are really starting to annoy me...

    For a certain model of car the distance d required to stop the vehicle if it is traveling at v mi/h is given by the formula

    d = v + \frac{v^2}{20}

    where d is measured in feet. Kerry wants her stopping distance not to exceed 240 ft. At what range of speeds can she travel?
    I have made a couple attempts at setting up this problem, but both have failed miserably so far. So some help setting it up will be appreciated.

    Also, since I am having so much trouble with application problems, is there any tips you guys can give me on how I should attack future math problems such as these? Thanks.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Moo
    Moo is offline
    A Cute Angle Moo's Avatar
    Joined
    Mar 2008
    From
    P(I'm here)=1/3, P(I'm there)=t+1/3
    Posts
    5,618
    Thanks
    6
    Hello,
    Quote Originally Posted by mathgeek777 View Post
    I have made a couple attempts at setting up this problem, but both have failed miserably so far. So some help setting it up will be appreciated.

    Also, since I am having so much trouble with application problems, is there any tips you guys can give me on how I should attack future math problems such as these? Thanks.
    The main tip I can give you for this is that you always must translate the sentences given in the text.

    Here : "she wants her stopping distance" << this is d "not to exceed 240ft", that is d<240.

    So you have to find v such that d = v + vē/20 < 240.
    Think "quadratic" !

    Advice : be careful, speed is in mi/h and distance in ft in the formula. So don't bother changing the units to be the same or wondering about them your result will automatically be in mi/h.


    Edit : woah... 28th post
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Rhymes with Orange Chris L T521's Avatar
    Joined
    May 2008
    From
    Chicago, IL
    Posts
    2,844
    Thanks
    3
    Quote Originally Posted by mathgeek777 View Post
    I have made a couple attempts at setting up this problem, but both have failed miserably so far. So some help setting it up will be appreciated.

    Also, since I am having so much trouble with application problems, is there any tips you guys can give me on how I should attack future math problems such as these? Thanks.
    Let d=240

    The equation then becomes 240=v+\frac{v^2}{20}\implies v^2+20v-4800=0

    Applying the quadratic formula, we see that v=\frac{-20\pm\sqrt{400+19200}}{2}\implies v=\frac{-20\pm140}{2}

    This implies that v=-80~or~v=60

    We take the positive value.

    So the maximum speed she can travel in order to break a distance of 240 ft would be 60 mph.

    I hope this makes sense!

    --Chris

    EDIT: Shucks...Moo beats me again...I guess the early cow gets the grass
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Member
    Joined
    Dec 2007
    From
    Georgia
    Posts
    85
    Thanks for the help guys. Maybe I should carefully look at a problem and figure out what I have and don't have first, rather than jump straight into it right away only to run into trouble.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. application problems
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: February 9th 2010, 01:30 AM
  2. Business Application Problems
    Posted in the Calculus Forum
    Replies: 1
    Last Post: October 25th 2009, 04:52 PM
  3. Application Problems
    Posted in the Algebra Forum
    Replies: 6
    Last Post: November 29th 2008, 12:30 PM
  4. application problems
    Posted in the Calculus Forum
    Replies: 7
    Last Post: June 3rd 2007, 04:22 PM
  5. A few antiderivative application problems
    Posted in the Calculus Forum
    Replies: 3
    Last Post: January 23rd 2007, 11:29 PM

Search Tags


/mathhelpforum @mathhelpforum